ian_sadler

When you get the bumpsteer done PS do the alignment first anyway.

I had alignment done by my dealer when the car was in for a service and I was still unhappy with the way the car drove so I went to PS and had the full monty done.

Saying that Subaru want the bumpsteer in the set up is like saying that subaru designed in piston slap its there but do you want it?

Quote:-
Powerstation Subaru Impreza Geometry Modification
A common complaint of Subaru Impreza owners is the tendency for their cars to understeer when pushed hard, whether on the road or race track. Powerstation decided to take this challenge on board and spent quite a while setting up a customer's car using various geometry changes to try and dial out this understeer. Using their very accurate geometry measuring equipment they saw that the Impreza suffers from what is known as bump steer. This is the tendency for the front wheels to splay outwards when the front suspension is loaded up due to weight transfer or under braking.


Ian

Edited to add quote from PS web site - Hope they dont mind

[Edited by ian_sadler - 10/2/2002 11:12:22 PM]

P1 Enthusiast

Very interested to know if ANYONE out there knows the difference that having a geometry alignment will have versus the alignment + bumpsteer.

Not really interested in your views on the bunpsteer itself unless you have had a geometry alignment carried out prior to it and then felt the bumpsteer was better again.

Graham from TSL (whose opinion i value) says the 1mm difference in the rack is not how Subaru wanted it or Prodrive and to trust them - however i need a geometry alignment and Power Engineering is closest - thus why would they sell a bumpsteer for 50 quid more than the alignment if it did nothing special?

<< Confused P1 owner!

LG John

I'm confused too on this one! Can someone outline exactly what both bumpsteer and geometry are? I think I've got geometry licked but I don't have a clue what bumpsteer is.

IWatkins

I'm saying nothing.... much.

Your ID says "Birmingham" but you say Power Engineering (Uxbridge, London way) is closer ? Sure you don't mean PowerStation (Cheltenham) ?

Anyway, no disrespect to Graham at TSL, but he obviously doesn't understand the bump steer mod. Trouser certainly didn't even know what bump steer was when asked on this board several months ago. First off, it isn't 1mm, it is variable amount based on the individual car. Second, doing the bump steer mod also means doing an alignment, they go hand in hand.

But saying that to leave it alone because Subaru designed it that way is just daft. I suppose Graham also suggests not buying an aftermarker exhaust ? Or clear indicators ? Or big brake conversions ?

Cheers

Ian

[Edited by IWatkins - 10/2/2002 11:48:56 PM]

ripmaze

The new WRX (>MY01) apparently has virtually no bump steer which gives it better front end grip than classic shape cars so I guess Subaru do want it removed! Although I've not driven a new shape so can't say - just repeating what others have said. I certainly find my MY99 keen to understeer when accelerating out of a corner which could be attributed to it.

ripmaze

I mean bug eyes - i.e. >MY00 (not >MY01 as I typed above!)

harvey

iTrader: (48)

The bump steer mod involves shimming the steering rack by a variable amount from car to car to suit each vehicles needs. The four wheel alignment MUST then be carried out.I had alignment carried out at Power Station and on a subsequent visit the bump steer was done.The alignment alone had a noticable effect but I was still somewhat unhappy. (What I did not know then was that a certain so called Scooby specialist company had fitted different front and rear diff ratios with a centre 1:1 dropper so no wonder the handling was somewhat odd) With the diffs sorted and the bump steer mod handling became awesome. Go for it. I would be very surprised if you did not think it was money well spent. I do not regret the long journies to Power Station for the steering mods I have had and I go that far because I am confident they have the right equipment and know how to use it.
To further confuse you ask them also about the anti-lift kit.

Stuart J

Ok
I went to Powerstation, had Geometry, antilift kit, bump steer & rear drop links all done at the same time. The car is an STI 3 & the improvement was fantastic, The first couple of corners I tried hard it turned in so well I almost thought the back was going to come round but soon got used to it & now its just "enjoy".
The only negative I have heard to bump steer (but not experienced) is that if you do a lot of motorway driving where the wheels are mainly straight you can experience some uneven tyre wear. I class myself as an average driver & if the motorway is the quickest route I take it & have not had uneven wear.

Ask all the questions of Powerstation before you make your mind up they are very helpful.

Stuart

Josh L

Well that's the bump steer, but the geometry is the key issue. Having the 4 wheel geometry checked and set to the middle of the tolerances transforms the car in itself.

A vast majority of dealers don't have access to Hunter equipment, and either just do the tracking, or farm it out. Although I was happy with my P1, Listers paid for the full check to try to sort out some uneven tyre wear (IM couldn't have cared less), and the difference was amazing. IM's tolerances are so wide I would recommend the check to anyone.

Maybe you should get the geometry checked at PS and then take the car for a spin before deciding on the bump steer.

Josh

GF8

Can the understeer that is caused by bumpsteer be minimized by driving technique? I am thinking that the amount of bumpsteer can be removed with additional steering input when the car is rolled.

harvey

iTrader: (48)

Rolled? Explain?

alcazar

iTrader: (2)

Here's my two penn'orth for what it's worth.
I haven't had either mod done, but do know of a car which had the geometry done, was tried, then had the bump steer mod, and was tried again.
Result over a twisty difficult test run was identical, and the guy could feel no difference after the b/s mod, but loads after the geometry.
Flame suit is now on for someone to shoot me down as he should prob have done it the other way or summat???
Alcazar

GF8

Harvey,

I mean the body roll of the car, which induce the bumpsteer when the strut is compressed.

mutant_matt

GF,

Not really because the designed in Bump Steer causes the tyres to toe out on suspension compression causing understeer. You will always be fighting the understeer unless you go slower. The BSM enables you to go faster into, through and out of corners and transforms the feel of the front end. I had it done on my MY00 and was stunned at the difference it makes.

Alcazar, without wanting to be rude, the difference is night and day and I fail to see how any decent driver couldn't tell the difference!!!

BTW, I was @ Powerstation yesterday in my STi 7 and whilst it had virtually no Bump Steer already, the difference the careful geometry setup they have done is fantasic. On top of that, I had the ALK, adjustable rear ARB, drop links, bushes and uprated mounts just for good measure. It's like having a new (and transformed handling) STi

Matt

turb0s

has anyone used Elite in Dagenham, Essex to do geometry setup???

rex11

I'm over in the states so there are few tuners with the knowledge of our across the pond counterparts. Anyone have the geometry settings and mods of there cars that haad the geometry and alignment done to it. Any help would be great.

AliG

I've got my car booked in at power engineering to have a few thisngs looked at and I thought I would get the 4 wheel alignment done while I was there

Any body know if they do the Bumpsteer mod as well or tis that just a powerstation thing

If anybody knows of poerw engineerings efforts in this field I would apreciate hearing about them just making up my mind if I should get them to leave the alignment and get it all done at powerstation as I dont want to pay for things twice

Thanks Ali G

mutant_matt

Ali,

Bump Steer Mod is PowerStation only (and is only required on the old shape). I've no idea how good PE are at this as I always go to PowerStation.

Matt

ak47mh

I am definitely going to visit Powerstation for the Bump Steer Mod with Geometry, Anti-Lift and Eibachs lowering springs after reading the many reviews.

I know I will defitely have to inform my insurance company of the Eibach lowering springs, yet do I have to tell them about the bumpsteer and anti-lift as well?

harvey

iTrader: (48)

Rex 11:My settings are: R Camber=-2deg each side Toe +2mins each.
F Camber=-1deg 30mins each side. Toe +5mins each side.
Camber bolts were necesary to get the rear up to -2deg. Otherwise set at maximum equal negative camber.
Power Station sell camber bolts which are basically eliptical bolts.
These settings work well for me and most of my handling issues are resolved now that I have the same diff ratio front and rear.!!!!!!

LG John

Right, thats it, I want them both done as I've heard too many good things about them and the handling on my scooby is pretty pants at the moment.

So, where in scotland can do both of these works and do a good job. Contact details with any recommendations would be appreciated

john banks

Falkland developed bumpsteer removal using my car as a guinea pig. It works well and seems to tame a lot of the understeer. With the sort of torque it has now I find the car a bit of a handful on occasion, particularly in the wet.

LG John

Cool, I heard they had the ability/facilities to do both I've actually been a little disapointed with the scoobs 4wd system. It's great in a straight-line but if you nail the gas mid bend the outside from wheel just starts to spin and the car will do one of two things; Plough straight on dump the power to the rear and give oversteer. Problem is I find it doesn't consistently do one or the other and I really need to know which it'll choose before I can make particularly rapid progress

GF8

Shouldn't the Prodrive geometry reduce some of the bump steer?

mutant_matt

Yes, but it's a compromise...

GF8

Moreover, will the bumpsteer be further reduced if suspension travel is decreased with lowering suspension system?

mutant_matt

The Bump Steer increases with suspension load so I guess so.

Matt

Sue Sidal

Matt, some questions for you please. I have a Jap Import STi7 and I'm interested to hear of the mods that you have had done at PS. I'm thick as **** and twice as chocolatey when it comes to all this technobabble so: 1. what do all the TLA's mean and, 2. What did it cost you. Thanks for your help.

Leslie

Just like to add my comments to the Bump Steer/alignment discussion. The meaning of B/steer has been explained well in a previous post and is absolutely valid. Of course you can offset poor suspension characteristics to a certain extent by the way you drive a car. I suggest you find someone who is prepared to let you drive their VW beetle round a few corners on a wet day so you can experience what real oversteer is all about! This is a car where you really have to modify your driving style in the wet! Once you have passed the point of no return once or twice then you might appreciate how important really good handling is to the enjoyment and safety factor of driving round corners quickly. Bump Steer of course relates to the ability of the front wheels to hang on in tight corners where the suspension is heavily loaded. If the front wheels splay outwards when the suspension is compressed then as the car rolls under a cornering load the outside wheel which is doing the most work as far as roadholding is concerned will have to have extra steering movement to compensate. The inside wheel naturally will also have extra lock applied which tends to make it "scrabble" thus decreasing its roadholding ability and causing uneven wear. The overall effect of this is to make it necessary to apply more lock and make the steering feel heavier and less controllable, as well as wearing the tyres unecessarily.

My STI 1 (MY94) seemed to be quite good round corners when I first had it but I noticed that the steering always felt undergeared and that I had to pin the front of the car into a tight corner very positively to avoid running wide. My front tyres were also wearing seriously quickly on the inside edges. I took the car to Power Station who aligned the suspension and demonstrated that their Bump Steer mod reduced the splay of the front wheels from 40 minutes to less than 2 minutes over the suspension travel. The suspension overall needed some alignment to get it exactly right but it was not too far out. The difference in handling was quite outstanding, the steering is lighter and very positive, the car feels absolutely balanced in the corners and the handling in the wet is superb. I later found also that replacing the soggy plastic rear anti roll bar links with the Whiteline steel ones further improved the feel of the steering such that it was evident on the first corner. The front STI roll bar links are properly designed and dont need replacing. The front tyres are wearing absolutely evenly too. This is a sign of well set up suspension geometry.

I suppose I had better defend my qualifications by saying that I drove racers for some years and used to design and build my own sports racing cars from the ground up.

Hope this helps

Les

CataIunya

With all that experience why not do the mod yourself ?